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91.
A cylindrical magnetic nanowire system composed of ferromagnetic core and shell layers has been investigated by using effective field theory (EFT) with correlations in the presence of transverse fields and surface shell amorphization. Both weak and strong exchange couplings at the core–shell interface have been considered. The main attention has been focused on the former situation where the system exhibits similar characteristic features with that observed in thin film and semi-infinite systems in which the surface effects are prominent. A complete picture of the phase diagrams and magnetization profiles has been represented and the effect of the surface shell amorphization on these properties has been discussed. Furthermore, we have investigated the ground state behavior of total magnetization mT curves and we have observed that mT curves exhibit highly non-monotonous and exotic ground states in the presence of frustration in the surface shell. We have also analyzed the necessary conditions for the occurrence of reentrant behavior in the system. 相似文献
92.
Amorphous aluminophosphate (AlP) and metal‐aluminophosphates (MAlPs, where M=2.5 mol%Cu, Zn, Cr, Fe, Ce, or Zr) were prepared by coprecipitation method. Their surface properties and catalytic activity ... 相似文献
93.
In this paper, we give a closed-form expression of the inversion and the connection coefficients for general basic hypergeometric polynomial sets using some known inverse relations. We derive expansion formulas corresponding to all the families within the q-Askey scheme and we connect some d-orthogonal basic hypergeometric polynomials. 相似文献
94.
95.
In this article,we consider the Bagley-Torvik type fractional differential equation ~cD~(ν1) l(t)-a~cD~(ν2) l(t) = g(t, l(t)) and differential inclusion ~cD~(ν1) l(t)-a~cD~(ν2) l(t) ∈ G(t, l(t)),t ∈(0, 1) subjecting to l(0) = l_0,and■ ds where 1 ν_1 ≤ 2, 1 ≤ν_2 ν_1,0 ω≤ 1, χ = ν_1-ν_2 0, a, λ′are given constants. By using Leray-Schauder degree theory and fixed point theorems, we prove the existence of solutions. Our results extend the existence theorems for the classical Bagley-Torvik equation and some related models. 相似文献
96.
Ahmed A. El‐Barbary Mahmoud A. El‐Badawi Yasser M. Loksha 《Journal of heterocyclic chemistry》2001,38(3):711-716
Some novel 3,7‐dimethyl‐6H‐pyrazolo[5,1‐c][1,2,4]triazin‐4‐ones were prepared (3a‐g) . Compounds 3a,b were treated with hydrazines to afford various products 7a,b, 8a,b, 9 and lla,b depending on the type of hydrazine derivative and reaction conditions. The benzoyloxyimino‐pyrazolo[5,1‐c][1,2,4]triazines (13a,b) were synthesized by refluxing of compounds 3a,b with hydroxylamine hydrochloride to afford the corresponding oxime derivatives followed by treatment with benzoyl chloride. 相似文献
97.
A. A. Hamza M. A. Mabrouk W. A. Ramadan M. A. Shams-Eldin 《Optics Communications》2001,200(1-6):131-138
The core–cladding refractive index difference Δn and the index gradient profile parameter of the graded index (GR-IN) optical fibre has been determined. The curve representing the real path, in the core region, due to refraction of the beam and the change in the exit wavefront are considered. Multiple-beam Fizeau fringes and two-beam interference Pluta polarizing microscope, are used for this investigation. A new method, based on a derived mathematical expression, is used with a prepared computer program to estimate the fringe shift inside GR-IN of the fibre core. The estimated and experimental values of the fringe shift, along the core radius, are used to obtain the refractive index profile of the optical fibre. A comparison between the new method and a previous model considering the refraction has been shown. Microinterferograms are given for illustrations. 相似文献
98.
Anis Hamza Fakeeh Muhammad Awais Naeem Wasim UllahKhan Ahmed Elhag Abasaee Ahmed Sadeq Al-Fatesh 《化学物理学报》2014,27(2):214-220
用浸渍法制备γ-Al2O3负载的Ni-Mn双金属催化剂.在500~700 oC按照17:17:2的CO2/CH4/N2比例,以36 mL/min的载气流速进行甲烷二氧化碳重整反应, 利用甲烷二氧化碳的转化率、生成的合成气H2/CO比例以及长期稳定性等指标评价了催化剂的催化性能. 实验表明, 添加Mn提高催化性能并使双金属催化剂的稳定性更高, 比单金属催化剂更好地抑制焦炭生成,Mn最合适的添加量0.5wt% .通过BET、CO2-TPD、TGA、XRD、SEM、EDX和FTIR各种技术对催化剂进行了表征. 相似文献
99.
Corresponding to n independent non-negative random variables X
1,...,X
n
, are values M
1,...,M
n
, where each M
i
is the expected value of the maximum of n independent copies of X
i
. We obtain an upper bound for the expected value of the maximum of X
1,...,X
n
in terms of M
1,...,M
n
. This inequality is sharp in the sense that the random variables can be chosen so that the bound is approached arbitrarily
closely. We also present related comparison results.
相似文献
100.
Khalil Hamza 《Tetrahedron letters》2007,48(2):293-295
Co-polycondensation of tetramethoxysilane, 2-diphenyl(phosphino)ethyltri(ethoxy)silane, and N-2-(aminoethyl)-3-aminopropyltri(methoxy)silane forms a heterogenized tertiary phosphine reagent (HPR) that reacts with benzyl chlorides and aldehydes to give alkenes. This Wittig condensation can be coupled, as a one-pot process, with hydrogenation, oxidation, bromination or photocyclization. 相似文献